Various accumulator apparatuses and methods have been employed in the past for accumulating sheet material or articles such as paper sheets, documents, and the like into stacks for subsequent advancement. Such accumulator apparatuses and methods have particular use in high-speed mail processing where preparation and processing of mailable articles (e.g., bills, account statements) often requires a plurality of sheets and/or articles to be assembled into a packet for further handling which can include, for example, folding, inserting, and collating.
Examples of conventional accumulator apparatuses are shown in U.S. Pat. No. 5,244,200 to Manzke; U.S. Pat. No. 5,775,689 to Moser et al., U.S. Pat. No. 6,203,006 to Semanick et al., and U.S. Pat. No. 6,712,354 to Semanick, each of these patents being commonly assigned herewith and incorporated herein by reference in its entirety. These references disclose an accumulator apparatus utilizing driven endless elastic belts that feed sheets therebetween along a sheet-feeding path. Ramps are provided to deflect sheets out of the sheet-feeding path and accumulate the sheets in an accumulator located between the ramps and a stop.
Consider U.S. Pat. No. 5,775,689 to Moser et al., as an example. FIGS. 1 and 2 show the device from that patent. As shown, accumulator apparatus 10 comprises an upper and a lower belt means adapted to convey sheets and/or articles therebetween. Each of the upper and lower belt means UB, LB comprises a plurality of spaced-apart endless elastic polycord belts driven by a suitable drive member. The upper belts UB include lower reaches 20 and the lower belts LB include upper reaches 22, as shown in FIGS. 1-2. The upper and lower belts UB, LB are driven so that lower and upper reaches 20, 22 move at substantially the same speed in a common direction through accumulator apparatus 10 to thereby define a generally horizontal conveyance of sheet and/or articles processed through accumulator apparatus 10, such as indicated by entry and exit arrows 12, 14, shown in FIG. 2.
At the accumulator apparatus 10 entrance, sheets and/or articles advance into the accumulator apparatus between the upper belts UB and lower belts LB, where entry roller guide means 40 are provided and comprise a plurality of upper guide rollers 42 fixedly attached in a spaced-apart relationship to rotatable shaft 44 and a plurality of lower guide rollers 46 fixedly attached in a spaced-apart relationship to rotatable shaft 48. The upper belt means UB and lower belt means LB respectively extend around upper guide rollers 42 and lower guide rollers 46, as shown in FIGS. 1-2. The upper guide rollers 42 and lower guide rollers 46, in operative association with upper belts UB and lower belts LB, respectively, guide sheets or articles advancing therebetween.
Accumulator apparatus 10 comprises ramp means 80 for deflecting sheets or articles processed between upper belt means UB and lower belt means LB from the horizontal feeding plane. Ramp means 80 can include a plurality of ramp members, such as side ramp members 82 and intermediate ramp members 82A which comprise deflecting surfaces 86 and slots 88 defined therein for extension therethrough of lower reaches 20 of upper belt UB.
Front rollers 100 and rear rollers 110 are spaced about respective shafts 84A, 84C of ramp means 80 to respectively engage the upper reaches 22 of lower belts LB and to align the feeding direction of sheets or articles through accumulator apparatus 10. Upper reaches 22 of lower belts LB extend over and engage front rollers 100 and extend from such above-engaging position with front rollers 100 downwardly and away from lower reaches 20 of upper belts UB where upper reaches 22 of lower belts LB extend engagingly below and past the bottom sides of rear rollers 110. Downstream from rear rollers 110, accumulator apparatus 10 includes a plurality of lower rollers 120 rotatably attached to a shaft, and lower belts LB extend around lower rollers 120 so as to reverse direction back toward lower guide rollers 46, as shown in FIGS. 1-2. Lower rollers 120 and lower guide rollers 46 of entry roller guides means 40 therefore are the outermost opposing rollers around which lower belts LB extend and cycle. Lower rollers 120 are located and maintained in a spaced-apart position from lower reaches 20 of upper belts UB.
Sheets or articles advancing through accumulator apparatus 10 between upper belts UB and lower belts LB will contact and be deflected by ramp members 82 and 82A out of the horizontal feeding plane and over upper edges 96. Lower reaches 20 of upper belts UB can also be diverted upwardly by ramp members 82. Downstream of upper edges 96, a deflected sheet article is urged back toward the horizontal feeding plane by resilient action of lower reaches 20 of upper belts UB due to their tension and/or diversion. Progressive feeding of sheets or articles in the horizontal feeding plane where the sheets or articles are deflected by ramp members 82 and 82A causes over-accumulation of sheets or articles in a stack or accumulation location past upper edges 96 of ramp members 82 and 82A. To support accumulated sheets or articles S, accumulator apparatus 10 comprises support means such as a plurality of spaced-apart supports 98 extending from ramp members 82A and supports 140. The leading edges of sheets or articles accumulated in stack S are positioned against and stopped by stop means 150. Upper stop rollers 152 and lower stop rollers 156 are output rollers adapted for selectively gripping, stopping, and advancing sheets or articles S.
As illustrated in the exemplary patents identified above, accumulators conventionally employ endless upper belts and lower belts for seriatim feeding of sheets or articles therebetween. A problem with accumulator apparatuses and methods employing such endless upper belts and lower belts, however, is that the upper and lower belts can cause smudging of ink or toner or can pick-up residual print material (e.g., ink or toner) from various sheets or other sources and convey the residual print material to other sheets. As shown in FIGS. 1-2, the conventional accumulators have polycord belts extending through the ramps up to the output shaft upon which the output rollers are disposed. While sheets or articles are transported over the ramps (e.g., ramp 80 in FIG. 2), and the sheets accumulate in the accumulator, the polycords continually rotate over the sheets, which causes marking on the sheets or articles.
Accordingly, there remains room for improvement in the art for an accumulator apparatus and method which reduces or eliminates inadvertent marking on the conveyed sheets or articles.